The disclosed embodiments relate to a medical device. Specifically, the disclosed embodiments relate to a catheter capable of efficiently transmitting an operator's pushing force to a distal end of the catheter, and capable of bending along curved regions of a blood vessel, bile duct, pancreatic duct or the like.
When a narrowed or obstructed segment is formed in a lumen (e.g., a blood vessel, bile duct, pancreatic duct, or the like), the flow of fluid (e.g., blood, bile (gall), pancreatic fluid, or the like) through the lumen may be hindered. Traditionally, treatments with a catheter have been widely performed to treat a narrowed or obstructed segment of a lumen. In order for the catheter to reach the narrowed or obstructed segment, the operator's pushing force needs to be efficiently transmitted to the distal end of the catheter. It is also important to avoid catching the catheter in a curved region of the lumen as the catheter is being pushed.
In order to improve the pushing force toward the distal end of the catheter, the catheter may include a core wire axially disposed between an outer tube and an inner tube. See, for example, WO 2006/126642 and Japanese Patent Application Laid-Open No. 2012-223207. One core wire is disposed in the catheter of WO 2006/126642, and multiple core wires are disposed in the catheter of Japanese Patent Application Laid-Open No. 2012-223207.
However, in the catheters of WO 2006/126642 and Japanese Patent Application Laid-Open No. 2012-223207, the core wire or wires are fixed to other members of the catheter (for example, the outer tube, the inner tube, a hypo tube, or the like), and thus have almost no degree of freedom. Therefore, when the catheter is inserted into a curved region of a lumen, the core wires cannot move to the optimal position within the catheter, causing the core wire to break. Additionally, the catheter may get caught in the curved region of the lumen when being pushed, preventing the catheter from reaching the target narrowed or obstructed segment.
Furthermore, although axial rigidity can be improved by using multiple core wires, the multiple core wires may interfere with each other (i.e., obstruct each other's movement) when the catheter is inserted into a curved region of a lumen. Significantly, this may prevent the catheter from bending along the lumen, preventing the catheter from reaching the target narrowed or obstructed segment.